Efficient Technology

Nancy Hartsoch explains how Concentrator Photovoltics (cpv) bring high-energy yield and low energy cost.

“CPV panels have reached efficiency levels above 25 percent, with significant headroom for accelerating improvements in efficiency”
-Nancy Hartsoch, SolFocus, Inc.

The challenge that has been facing solar for over a decade in its drive to become a mainstream renewable technology has been cost. The most important element in determining the levelized cost of energy, is the efficiency of the panels; in other words, the amount of sunlight that can be converted to electricity. The second important element is manufacturability of technology. If new technologies are going to become mainstream energy sources, they must be designed for low-cost, high-volume manufacturability.

Concentrator photovoltaic (CPV) systems are the newest entrant into the commercial solar market. CPV technology has just moved into commercialization, yet already these systems are proving their ability to provide the lowest cost solar energy and the highest energy harvesting capability in the high solar resource regions of the world.

CPV systems convert light energy into electrical energy the same way that conventional photovoltaic technology does. The difference with concentrator PV is the addition of an optical system that focuses a large area of sunlight onto each cell. Also, the cells used in CPV systems are different from silicon PV cells, and are capable of converting very large amounts of sunlight into energy at high efficiency, which allows the optical systems to be used. With high concentration systems such as SolFocus’ SF-1100S, a multi-junction cell of 1 cm squared is illuminated by the sun, magnified 650 times. The result is that the cell, per unit of energy, costs dramatically less than that of conventional photovoltaic technologies.

Even with advances in traditional silicon PV where today you can find best-in-class panels with 19 percent efficiency (average of 15 percent), CPV panels have reached efficiency levels above 25 percent, with significant headroom for accelerating improvements in efficiency in the near future. These CPV panels are mounted on dual-axis trackers, which keep the panels in direct alignment with the sun. The combination of high-performance optics, high-efficiency cells and precise tracking allows CPV systems to deliver advantages not available with other solar technology approaches. CPV technology also provides environmental sustainability. Land use is optimized, there is no permanent shadowing, no water is consumed in the production of electricity and systems are highly recyclable with a small carbon footprint.

CPV case study
The first true case study in CPV technology was established last year by The Institute of Concentration Photovoltaic Systems (ISFOC) in Puertollano, Spain – a public-private partnership promoted by the Castilla La Mancha Government and the Universidad Politécnica de Madrid. Within this project, ISFOC is executing 3MW of power plant capacity, incorporating different concentrator technologies, which are becoming available in the market. It is a commercial power plant providing energy to the local community, as well as a research site for the implementation of the technology. ISFOC has become a world-recognized reference in CPV.

“Our ISFOC project has been critical in moving CPV forward at industrial scale,” explained Dr. Pedro Banda, Director General of ISFOC. “After a year of deployment, we have no doubt that CPV is the most promising energy resource for the future.”

SolFocus was the first company to install its CPV technology in the project and has had 0.5MW on site for a year. After nearly a year, energy output has been above projected levels.

“We chose SolFocus’ CPV arrays as part of the ISFOC project because we believed their non-imaging optical design would provide efficient and reliable systems,” said Dr. Pedro Banda. “We had confidence that they would be able to meet not just the design challenges, but the manufacturing challenges for volume deployment as well; we could not be more pleased with the results.”

While Puertollano, Spain has a good solar resource, the energy generation capability of this type of power plant in high solar resource region such as southwest US, will be exceptional. CPV systems are being deployed in numerous places around the world and have the potential to deliver hundreds of megawatts of electricity in the near future.

Nancy Hartsoch is the Vice President of Marketing for SolFocus, Inc. Prior to joining the company she was CEO of Pacific Technology Group and COO/ VP of Acer Labs USA. In 2008 Nancy was instrumental in forming the CPV Consortium, a global industry organization for which she currently is the Chairperson.